Internal combustion engine



FIG. 1 is a perspective view of an internal combustion engine.

FIG. 2 is a perspective view thereof.

FIG. 3 is a front elevation view thereof.

FIG. 4 is a rear elevation view thereof.

FIG. 5 is a top plan view thereof.

FIG. 6 is a bottom plan view thereof.

FIG. 7 is a left side elevation view thereof; and,

FIG. 8 is a right side elevation view thereof. 

The ornamental design for an internal combustion engine, as shown and described. 